The use of free transplants in restoring orbital deformities.

The orbit is the one anatomical region where the domain of the plastic surgeon overlaps those of the otorhinolaryngologist, the neurosurgeon and the ophthalmologist. The subject is therefore of fairly wide interest to specialists and general practitioners. The emphasis will be placed more on principles than on details. The anatomical orbit' is the area enclosed by the bony walls of the orbit, but the region referred to in this paper is taken to be that which is generally included in the clinical use of the term, viz. the orbital contents, orbital margins and their integumentary cover. This would then include the eyelids-which, to a varying extent, may be situated anterior to the true orbit-the malar prominence, and the eyebrows. The transplants that are to be discussed may be classified as: (a) those consisting of normal body tissues and (b) those consisting of alloplastic materials. Normal body-tissue grafts may consist of bone, cartilage, fat, fat and dermis, fascia, skin, or mucosa. These body tissues may in turn be used as autografts, homografts, or heterografts. Alloplastic materials used may consist of either solids or fluids. Fluids were used at one stage in the form of injections of liquid paraffin, but this has gone completely out of fashion due to the development of paraffinoma tumours. The use of silastic fluid is today being extensively investigated, but is not in general use, due to the irretrievability of the fluid once it has been injected.'" In animal experiments this fluid has been shown to be completely dispersed, and in fact even to be taken up by the macrophages in viscera in remote parts of the body. Solids which are used as transplants consist of a variety of types. Thus the following materials have at one time or other been used: gold, silver, alloys such as vitallium, ivory, stainless steel, various plastic materials such as celluloid, Supramid, plexiglass, polyethylene, Polystan, mcthylmethacrylate, Paladon, ivalon, etheron and the different types of medical grades of silicone rubber. Scales' pQstulates the following properties for any implant which must act as a synthetic tissue substitute: 1. It must not be physically modified by the soft tissue. 2. It must be chemically inert. 3. There must be no inflammatory or foreign-body reaction to it. 4. It must be non-carcinogenic. 5. It must not produce any allergy or hypersensitivity at any stage. 6. It must be capable of resisting mechanical strains. 7. It must be capable of fabrication in the form desired. 8. It must be capable of sterilization. Of all the synthetic materials available to us today, the medical grade silicones seem to conform most closely to the above requirements as they are heat stable, unaffected by time, non-adherent to tissues, and elicit no tissue re-